This invention relates to a metal polishing slurry for use in chemical mechanical polishing planarization in the manufacture of semiconductor devices. This invention also relates to a polishing method using such metal polishing slurry.
In the development of semiconductor devices such as semiconductor integrated circuits (hereinafter referred to as “LSI devices”), the trend toward smaller sizes and higher processing speeds has created a need in recent years for higher density and higher integration by the adoption of miniaturization and multilayer constructions of interconnection. Various techniques are being used to this end, including chemical mechanical polishing (hereinafter also referred to as “CMP”).
CMP is an essential technique for carrying out, for example, the surface planarization of a film to be processed (e.g., an interlayer dielectric film), plug formation, and buried metal interconnect formation, and this technology is used to carry out substrate planarization and to remove surplus metal thin film during the formation of interconnections. (See U.S. Pat. No. 4,944,836 B and JP 2-278822 A.)
CMP generally involves attaching a polishing pad onto a circular platen, impregnating the surface of the polishing pad with a polishing slurry, pressing the right side of a substrate (wafer) against the pad, and rotating both the platen and the substrate while applying a predetermined pressure (polishing pressure) from the back side of the substrate so as to planarize the right side of the substrate by the mechanical friction that arises.
The metal polishing slurry used in CMP typically includes fine abrasive particles (such as alumina and silica) and an oxidizer (such as hydrogen peroxide). It is believed that polishing takes place with oxidization of the metal surface by the oxidizer and removal of the resulting oxide film by the abrasive. The detailed procedure is described, for example, in Journal of Electrochemical Society, 1991, vol. 138, No. 11, pages 3460 to 3464.
However, the CMP conducted by using such metal polishing slurry containing the solid abrasive is associated with the risk of scratches formed by the polishing (scratches), excessive polishing of the entire polishing surface (thinning), deformation of the polished metal surface in the shape of a dish (dishing), and excessive polishing of the insulator between the metal interconnect wiring and dish-shape deformation of the wired metal surface (erosion).
JP 8-64594 A and JP 8-83780 A, for example, refer to incorporation of 1,2,3-benzotriazole or 2-aminothiazole in the polishing slurry as a means for suppressing such drawbacks, and in particular, the dishing. JP 2005-116987 A discloses that use of a benzotriazole derivative is effective in reducing the dishing.